/* CSS Reset and Base Styles */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --secondary-color: #64748b;
    --background: #0f172a;
    --surface: #1e293b;
    --surface-light: #334155;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --border-color: #475569;
    --success: #22c55e;
    --error: #ef4444;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3), 0 2px 4px -2px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.3), 0 4px 6px -4px rgba(0, 0, 0, 0.2);
    --radius: 12px;
    --radius-sm: 8px;
}

html {
    font-size: 16px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
    background: var(--background);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
}

/* Container */
.container {
    max-width: 600px;
    margin: 0 auto;
    padding: 2rem 1rem;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    text-align: center;
    margin-bottom: 2rem;
}

.logo-container {
    margin-bottom: 1rem;
}

.logo {
    width: 80px;
    height: 80px;
    object-fit: contain;
}

header h1 {
    font-size: 2rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-color), #a855f7);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.5rem;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
}

/* Main Content */
main {
    flex: 1;
}

/* Controls Section */
.controls {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
    margin-bottom: 1.5rem;
}

.input-group {
    margin-bottom: 1.25rem;
}

.input-group:last-of-type {
    margin-bottom: 1.5rem;
}

.input-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

input[type="number"],
select {
    width: 100%;
    padding: 0.75rem 1rem;
    font-size: 1rem;
    color: var(--text-primary);
    background: var(--surface-light);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    transition: border-color 0.2s, box-shadow 0.2s;
}

input[type="number"]:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

select {
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%2394a3b8'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'%3E%3C/path%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 0.75rem center;
    background-size: 1.25rem;
    padding-right: 2.5rem;
}

/* Decimal Options */
.decimal-options {
    display: none;
}

.decimal-options.visible {
    display: block;
}

/* Checkbox */
.checkbox-group {
    margin-top: 0.5rem;
}

.checkbox-label {
    display: flex;
    align-items: center;
    cursor: pointer;
    font-size: 0.9375rem;
    color: var(--text-primary);
    user-select: none;
}

.checkbox-label input[type="checkbox"] {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.checkmark {
    width: 22px;
    height: 22px;
    background: var(--surface-light);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    margin-right: 0.75rem;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.checkbox-label input:checked ~ .checkmark {
    background: var(--primary-color);
    border-color: var(--primary-color);
}

.checkbox-label input:checked ~ .checkmark::after {
    content: '';
    width: 6px;
    height: 10px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg);
    margin-bottom: 2px;
}

.checkbox-label:hover .checkmark {
    border-color: var(--primary-color);
}

/* Buttons */
.btn-primary,
.btn-secondary {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.875rem 1.5rem;
    font-size: 1rem;
    font-weight: 600;
    border: none;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: all 0.2s;
}

.btn-primary {
    width: 100%;
    background: linear-gradient(135deg, var(--primary-color), #7c3aed);
    color: white;
    box-shadow: var(--shadow);
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-hover), #6d28d9);
    transform: translateY(-1px);
    box-shadow: var(--shadow-lg);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    background: var(--surface-light);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    padding: 0.625rem 1rem;
    font-size: 0.875rem;
}

.btn-secondary:hover {
    background: var(--border-color);
}

.btn-icon {
    font-size: 1.125rem;
}

/* Results Section */
.results {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

.results-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.results-header h2 {
    font-size: 1.125rem;
    font-weight: 600;
}

.results-container {
    background: var(--surface-light);
    border-radius: var(--radius-sm);
    padding: 1rem;
    min-height: 100px;
    max-height: 300px;
    overflow-y: auto;
}

.placeholder {
    color: var(--text-secondary);
    text-align: center;
    padding: 2rem 0;
}

.number-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.number-item {
    background: var(--background);
    color: var(--text-primary);
    padding: 0.5rem 0.75rem;
    border-radius: 6px;
    font-family: 'SF Mono', Monaco, 'Courier New', monospace;
    font-size: 0.9375rem;
    border: 1px solid var(--border-color);
}

.single-number {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    color: var(--primary-color);
    padding: 1rem 0;
    font-family: 'SF Mono', Monaco, 'Courier New', monospace;
}

/* Toast Notification */
.toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    background: var(--surface);
    color: var(--text-primary);
    padding: 0.875rem 1.5rem;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
    opacity: 0;
    transition: all 0.3s ease;
    z-index: 1000;
}

.toast.show {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

.toast.success {
    border-color: var(--success);
}

.toast.error {
    border-color: var(--error);
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem 0 1rem;
    margin-top: auto;
}

footer p {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

footer a:hover {
    color: var(--primary-hover);
    text-decoration: underline;
}

/* Scrollbar */
.results-container::-webkit-scrollbar {
    width: 6px;
}

.results-container::-webkit-scrollbar-track {
    background: var(--surface);
    border-radius: 3px;
}

.results-container::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 3px;
}

.results-container::-webkit-scrollbar-thumb:hover {
    background: var(--secondary-color);
}

/* Responsive Design */
@media (max-width: 480px) {
    .container {
        padding: 1.5rem 1rem;
    }

    header h1 {
        font-size: 1.75rem;
    }

    .controls,
    .results {
        padding: 1.25rem;
    }

    .single-number {
        font-size: 2rem;
    }

    .number-item {
        font-size: 0.875rem;
        padding: 0.375rem 0.625rem;
    }
}

/* Animation for generating */
@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

.generating {
    animation: pulse 0.5s ease-in-out;
}

/* Error State */
.error-message {
    color: var(--error);
    font-size: 0.875rem;
    margin-top: 0.5rem;
}

input.error {
    border-color: var(--error);
}

input.error:focus {
    box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.2);
}